2,934 research outputs found
It’s all relative: the small craft museum's contribution to intangible cultural heritage
The Heritage Crafts Association’s Radcliffe Red List of Endangered Crafts illustrates the importance of perpetuating the intangible cultural heritage of heritage crafts in the UK. This study considers the ways in which small craft museums contribute to the UK’s intangible cultural heritage. This is achieved through the exploration of five small heritage craft museums: The Clockmakers’ Museum, The Fan Museum, The Lace Guild Museum, The Quilt Museum and Gallery, and The Stained Glass Museum.
This study seeks to elucidate the characteristics of these individual organisations, each of which serve two separate yet mutually dependent purposes that are atypical for most museums; 1) the perpetuation of their specific heritage craft and 2) the support of the individual communities of people that have a connection to the craft and without whom the specific craft practice could face extinction. This thesis is concerned with the importance of these heritage crafts in so far as they are the ‘raison d’être’ of each of these small museums, rather than a definitive exploration of the minutia and skills required for the individual handcrafts.
This thesis demonstrates that small heritage craft museums offer an important avenue for the continuous transfer of explicit and tacit knowledge between craft practitioners and non-practitioners and an important resource for practical and social interaction through their communities of practice. The continued viability of these museums and their heritage crafts is contingent upon inspiring future generations to actively engage in perpetuating the intangible cultural heritage of these crafts
Prospects for Probing the Spacetime of Sgr A* with Pulsars
The discovery of radio pulsars in compact orbits around Sgr A* would allow an
unprecedented and detailed investigation of the spacetime of the supermassive
black hole. This paper shows that pulsar timing, including that of a single
pulsar, has the potential to provide novel tests of general relativity, in
particular its cosmic censorship conjecture and no-hair theorem for rotating
black holes. These experiments can be performed by timing observations with 100
micro-second precision, achievable with the Square Kilometre Array for a normal
pulsar at frequency above 15 GHz. Based on the standard pulsar timing
technique, we develop a method that allows the determination of the mass, spin,
and quadrupole moment of Sgr A*, and provides a consistent covariance analysis
of the measurement errors. Furthermore, we test this method in detailed mock
data simulations. It seems likely that only for orbital periods below ~0.3 yr
is there the possibility of having negligible external perturbations. For such
orbits we expect a ~10^-3 test of the frame dragging and a ~10^-2 test of the
no-hair theorem within 5 years, if Sgr A* is spinning rapidly. Our method is
also capable of identifying perturbations caused by distributed mass around Sgr
A*, thus providing high confidence in these gravity tests. Our analysis is not
affected by uncertainties in our knowledge of the distance to the Galactic
center, R0. A combination of pulsar timing with the astrometric results of
stellar orbits would greatly improve the measurement precision of R0.Comment: 12 pages, 10 Figures, accepted for publication in Ap
Two-Dimensional Chiral Matrix Models and String Theories
We formulate and solve a class of two-dimensional matrix gauge models
describing ensembles of non-folding surfaces covering an oriented, discretized,
two-dimensional manifold. We interpret the models as string theories
characterized by a set of coupling constants associated to worldsheet
ramification points of various orders. Our approach is closely related to, but
simpler than, the string theory describing two-dimensional Yang-Mills theory.
Using recently developed character expansion methods we exactly solve the
models for target space lattices of arbitrary internal connectivity and
topology.Comment: 12 pages, 1 figure, TeX, harvmac.tex, epsf.tex, minor correction
Prospects for probing strong gravity with a pulsar-black hole system
The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected
to provide a superb new probe of relativistic gravity and BH properties. Apart
from a precise mass measurement for the BH, one could expect a clean
verification of the dragging of space-time caused by the BH spin. In order to
measure the quadrupole moment of the BH for testing the no-hair theorem of
general relativity (GR), one has to hope for a sufficiently massive BH. In this
respect, a PSR orbiting the super-massive BH in the center of our Galaxy would
be the ultimate laboratory for gravity tests with PSRs. But even for gravity
theories that predict the same properties for BHs as GR, a PSR-BH system would
constitute an excellent test system, due to the high grade of asymmetry in the
strong field properties of these two components. Here we highlight some of the
potential gravity tests that one could expect from different PSR-BH systems,
utilizing present and future radio telescopes, like FAST and SKA.Comment: Proceedings of IAUS 291 "Neutron Stars and Pulsars: Challenges and
Opportunities after 80 years", J. van Leeuwen (ed.); 6 pages, 3 figure
Diffractive and refractive timescales at 4.8 GHz in PSR B0329+54
We present the results of flux density monitoring of PSR B0329+54 at the
frequency of 4.8 GHz using the 32-meter TCfA radiotelescope. The observations
were conducted between 2002 and 2005. The main goal of the project was to find
interstellar scintillation (ISS) parameters for the pulsar at the frequency at
which it was never studied in detail. To achieve this the 20 observing sessions
consisted of 3-minute integrations which on average lasted 24 hours.
Flux density time series obtained for each session were analysed using
structure functions. For some of the individual sessions as well as for the
general average structure function we were able to identify two distinctive
timescales present, the timescales of diffractive and refractive
scintillations. To the best of our knowledge, this is the first case when both
scintillation timescales, t_DISS=42.7 minutes and t_RISS=305 minutes, were
observed simultaneously in a uniform data set and estimated using the same
method.
The obtained values of the ISS parameters combined with the data found in the
literature allowed us to study the frequency dependence of these parameters
over a wide range of observing frequencies, which is crucial for understanding
the ISM turbulence. We found that the Kolmogorov spectrum is not best suited
for describing the density fluctuations of the ISM, and a power-law spectrum
with beta =4 seems to fit better with our results. We were also able to
estimate the transition frequency (transition from strong to weak scintillation
regimes) as 10.1 GHz, much higher than was previously predicted. We were also
able to estimate the strength of scattering parameter u=2.67$ and the Fresnel
scale as 6.7x10^8 meters.Comment: 11 pages, 4 figures, accepted for publication in: Astronomy and
Astrophysic
Modeling the non-recycled Fermi gamma-ray pulsar population
We use Fermi Gamma-ray Space Telescope detections and upper limits on
non-recycled pulsars obtained from the Large Area Telescope (LAT) to constrain
how the gamma-ray luminosity L depends on the period P and the period
derivative \dot{P}. We use a Bayesian analysis to calculate a best-fit
luminosity law, or dependence of L on P and \dot{P}, including different
methods for modeling the beaming factor. An outer gap (OG) magnetosphere
geometry provides the best-fit model, which is L \propto P^{-a} \dot{P}^{b}
where a=1.36\pm0.03 and b=0.44\pm0.02, similar to but not identical to the
commonly assumed L \propto \sqrt{\dot{E}} \propto P^{-1.5} \dot{P}^{0.5}. Given
upper limits on gamma-ray fluxes of currently known radio pulsars and using the
OG model, we find that about 92% of the radio-detected pulsars have gamma-ray
beams that intersect our line of sight. By modeling the misalignment of radio
and gamma-ray beams of these pulsars, we find an average gamma-ray beaming
solid angle of about 3.7{\pi} for the OG model, assuming a uniform beam. Using
LAT-measured diffuse fluxes, we place a 2{\sigma} upper limit on the average
braking index and a 2{\sigma} lower limit on the average surface magnetic field
strength of the pulsar population of 3.8 and 3.2 X 10^{10} G, respectively. We
then predict the number of non-recycled pulsars detectable by the LAT based on
our population model. Using the two-year sensitivity, we find that the LAT is
capable of detecting emission from about 380 non-recycled pulsars, including
150 currently identified radio pulsars. Using the expected five-year
sensitivity, about 620 non-recycled pulsars are detectable, including about 220
currently identified radio pulsars. We note that these predictions
significantly depend on our model assumptions.Comment: 26 pages, 10 figures, Accepted by ApJ on 8 September 201
A sample of low energy bursts from FRB 121102
We present 41 bursts from the first repeating fast radio burst discovered
(FRB 121102). A deep search has allowed us to probe unprecedentedly low burst
energies during two consecutive observations (separated by one day) using the
Arecibo telescope at 1.4 GHz. The bursts are generally detected in less than a
third of the 580-MHz observing bandwidth, demonstrating that narrow-band FRB
signals may be more common than previously thought. We show that the bursts are
likely faint versions of previously reported multi-component bursts. There is a
striking lack of bursts detected below 1.35 GHz and simultaneous VLA
observations at 3 GHz did not detect any of the 41 bursts, but did detect one
that was not seen with Arecibo, suggesting preferred radio emission frequencies
that vary with epoch. A power law approximation of the cumulative distribution
of burst energies yields an index that is much steeper than the
previously reported value of . The discrepancy may be evidence for a
more complex energy distribution. We place constraints on the possibility that
the associated persistent radio source is generated by the emission of many
faint bursts ( ms). We do not see a connection between burst
fluence and wait time. The distribution of wait times follows a log-normal
distribution centered around s; however, some bursts have wait times
below 1 s and as short as 26 ms, which is consistent with previous reports of a
bimodal distribution. We caution against exclusively integrating over the full
observing band during FRB searches, because this can lower signal-to-noise.Comment: Accepted version. 16 pages, 7 figures, 1 tabl
Complete genome sequence and construction of an infectious full-length cDNA clone of a cucumber vein yellowing virus (CVYV) isolate from Portugal
Cucumber vein yellowing virus (CVYV) is a member of the genus Ipomovirus in the family Potyviridae. In the National Center for Biotechnology Information (NCBI) database, three complete genome sequences of CVYV isolates from Spain (NC_006941), Israel (KT276369), and Jordan (JF460793) are available. In this study, we report the complete sequence of an isolate of CVYV from Portugal (DSMZ PV-0776) along with the construction of an infectious full-length cDNA clone via Gibson assembly. The sequence of CVYV Portugal shows the closest relationship to a CVYV isolate from Spain (genome, 99.7% identity; polyprotein, 99.7% identity). The CVYV full-length cDNA clone was introduced by electroporation into Rhizobium radiobacter and infiltrated into the cotyledons of Cucumis sativus plantlets, resulting in symptoms resembling those of the wild-type virus. Transmission of the infectious CVYV full-length clone by the whitefly Bemisia tabaci was confirmed. This first report confirming the infectivity of a CVYV cDNA clone provides the opportunity to study gene functions in a consistent genomic background
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